Public Order Act 1986.
Section 4 – Fear or Provocation of Violence
Section 4 covers the offence of causing another person to fear for their safety and of provoking violence – either provoking violence to be used against that person or by that person towards another. Do not get section 4 confused with section 4a which is concerned with harassment, alarm and distress, but not violence.
(1)A person is guilty of an offence if he—
(a)uses towards another person threatening, abusive or insulting words or behaviour, or
(b)distributes or displays to another person any writing, sign or other visible representation which is threatening, abusive or insulting, with intent to cause that person to believe that immediate unlawful violence will be used against him or another by any person, or to provoke the immediate use of unlawful violence by that person or another, or whereby that person is likely to believe that such violence will be used or it is likely that such violence will be provoked.
(2)An offence under this section may be committed in a public or a private place, except that no offence is committed where the words or behaviour are used, or the writing, sign or other visible representation is distributed or displayed, by a person inside a dwelling and the other person is also inside that or another dwelling.
(3)A constable may arrest without warrant anyone he reasonably suspects is committing an offence under this section.
(4)A person guilty of an offence under this section is liable on summary conviction to imprisonment for a term not exceeding 6 months or a fine not exceeding level 5 on the standard scale or both.